While driving with the cruise set I wanted to reduce speed and hit the minus speed button on the cruise control which caused the vehicle to speed up which made me hit it quickly a couple more times to slow it down and it responded by speeding up more and led me to slam on the brakes. Luckily no one was in front of me so I didn’t rear end them when it sped up and no one was behind me that could have rear ended me when I slammed on the brakes.